Morphology and Molecular Phylogeny of Pseudocercospora rubigena Associated with Leaf Spot on Rubus corchorifolius in Korea

Pseudocercospora rubigena is a recently introduced leaf spot pathogen on Rubus sp. based on single-strain identification. This study addressed the limitations of the initial description of Ps. rubigena by examining multiple isolates of Rubus corchorifolius in Korea, emphasizing its first confirmed occurrence on this host. Notably, shorter conidia with a narrow septation range are considered key characteristics that distinguish Ps. rubigena from related species. Sequences of the internal transcribed spacer (ITS) region, along with protein-coding genes such as partial actin (actA), partial translation elongation factor 1-alpha (tef1), and partial DNA-directed RNA polymerase II second-largest subunit (rpb2), were obtained from three Korean isolates. Later, these sequences were included in phylogenetic analyses using a multigene dataset of ITS, act, tef1 and rpb2. The results showed that Pseudocercospora isolates from R. corchorifolius clustered in a single clade with Ps. rubigena, thus confirming the consistency between their morphological characteristics and those of the latter. This study clarifies the morphological and molecular phylogeny of Ps. rubigena, contributing to the taxonomy of Pseudocercospora species and providing insights into its host specificity and distribution.